A groundbreaking test which indicates whether chemotherapy will be effective could spare low risk breast cancer patients from unnecessary treatment.

Until now, women with early stage breast cancer have taken the drugs as a precautionary measure following surgery or radiotherapy.

But with the new test indicating the likelihood of the cancer returning, patients will be able to make a more informed decision.

The Telegraph reported that around 46% of women with newly diagnosed early-stage breast cancer were deemed low risk by the test and did not need the medication.

MammaPrint searches for 70 genetic variants which make the threat of cancer returning more likely, and is considered an effective indicator of whether patients can avoid chemotherapy.

While around 55,000 women in Britain are diagnosed with breast cancer each year, 71% of cases are picked up at an early stage.

The test, which has been trialled on 6,600 women over five years, has been deemed to accurately predict who needed chemotherapy.

Patients can currently only access the test privately at a cost of £2,000, but the Telegraph reported that the developer is in discussions with the National Institute of Health and Care Excellence about NHS provision.

Dr Maggie Cheang, senior staff scientist at The Institute of Cancer Research, London, told the Telegraph: “The trial clearly shows that patients with a low risk, defined by both clinical factors and the MammaPrint test, have an excellent prognosis and can be safely spared chemotherapy.

“However, in the group of patients that are clinically high risk but MammaPrint low, the benefit of chemotherapy and the survival beyond 5 years is still unclear. In this group, longer follow-up and future studies are needed before we decide to forego adjuvant chemotherapy.”